1. Technical Field
The present disclosure relates to a spectrometry device, an image forming apparatus, and a spectrometry method.
2. Related Art
In the related art, in an image forming apparatus such as a printer, there is known a device that includes a colorimeter measuring the color of an image recorded on a medium. See, for example, JP-A-2013-238755.
The device disclosed in JP-A-2013-238755 includes a recording head that forms (prints) an image on a medium and a colorimetric sensor for measuring the color of the image on the medium. The recording head and the colorimetric sensor are disposed separately, and the colorimetric sensor is pressed by a pressing plate to perform colorimetry on the medium.
The distance between the colorimetric sensor and the medium may be changed by, for example, a ripple on the medium or distortion of a transport path of the medium. As such, if the distance between the colorimetric sensor and the medium is changed, a light intensity distribution is changed at a position of measurement (i.e., in a range of measurement) where the colorimetric sensor performs colorimetry.
For example, if a colorimetry process is performed by irradiating the medium with light from a light source at an angle of incidence of 0° and detecting light reflected at an angle of reflection of 45° with the colorimetric sensor, the position of measurement is changed by a change in the distance between the colorimetric sensor and the medium. The light from the light source with which the medium is irradiated has a large intensity in the central portion thereof and a small intensity in the peripheral portion thereof. Thus, if the position of measurement is shifted, the light intensity distribution at the position of measurement is changed.
In addition, if the colorimetry process is performed by irradiating the medium with light from the light source at an angle of incidence of 45° and detecting light reflected at an angle of reflection of 0° with the colorimetric sensor, a position of irradiation with light from the light source is changed by a change in the distance between the colorimetric sensor and the medium. As described above, since the light from the light source with which the medium is irradiated has a large intensity in the central portion thereof and a small intensity in the peripheral portion thereof, the light intensity distribution at the position of measurement is changed if the position of irradiation is changed.
As such, if the light intensity distribution at the position of measurement is changed (e.g., decreased), the intensity of light received by the colorimetric sensor is also decreased, and measurement accuracy (i.e., color difference ΔE) is decreased if the colorimetry process is performed based on the measured intensity of received light.